This invention relates generally to electrical connectors and, more particularly, to connectors for making electrical connections with the terminals of printed wiring boards and the like.
Typically, a connector for a printed wiring board comprises an assembly with a slot to accept an edge of the board and with resilient contact members in the slot to connect to the electrical terminals of the board. Substantial force may frequently be required to insert a printed wiring board into a connector slot having a large number of resilient contact members therein due to the resilient engaging force of the contacts with the edge of the board. A common result of such direct insertion of boards into connectors with resilient contact members is to damage the electrical terminals of the board as well as to wear the resilient contact members. It is a common practice, therefore, to provide a connector in which the resilient contact members are removed from the insertion path of the board whereby no resistance is encountered during insertion of the board into the connector.
One example of a zero insertion force connector is shown in U.S. Pat. No. 3,793,609 issued Feb. 19, 1974, to W. McIver. This patent discloses an elongated cam member insertable between a pair of rows of resilient contact members to retract temporarily the resilient contact members for insertion therebetween of a printed wiring board. The elongated cam member is rotated to engage and to retract the resilient contact members to allow insertion of the printed wiring board. After insertion of the board, the cam member is again rotated to disengage the resilient contact members thereby connecting the contact members to the electrical terminals of the board.
Other examples of zero insertion force connectors are shown in U.S. Pat. No. 4,077,688 issued Mar. 7, 1978, to R. F. Cobaugh, et al.; U.S. Pat. No. 4,148,537 issued Apr. 10, 1979, to J. R. Sochor; and U.S. Pat. No. 4,159,154 issued June 26, 1979, to B. K. Arnold. The apparatus of these patents are characterized by the provision of facilities for retracting a pair of rows of opposing resilient contact members for insertion therebetween of a printed wiring board. The retractiion is accomplished by two retractor elements each engaging a nonopposing portion of a row of the resilient contact members and a cam element. Upon actuation of the cam element, the cam and retractor elements slide against one another thereby spreading the retractor elements apart which in turn retract the opposing resilient contact members. Upon insertion of a board therebetween and actuation of the cam in a reverse direction, the resilient contact members engage the electrical terminals of the board.
Among the disadvantages of these prior art zero insertion force connectors is the fact that, they receive only printed wiring boards having fixed electrical terminals, they depend upon the resiliency of the contact members to make electrical connections with the electrical terminals of the printed wiring board, and they are constructed with materials having limited durability under repeated usage.
It is an objective of this invention to provide a durable connector for making contact with the electrical terminals of a plurality of printed wiring boards with zero force. A second objective is to provide a connector to receive printed wiring boards having either fixed or resilient electrical terminals. A third objective is to provide a connector having positive means for making contact with the electrical terminals of a printed wiring board.